7. TB-SUBSYSTEM (8 bytes)

Entering a name of a VTS-TSR in this field completely bypasses the use of the local TSR in favor of the VTS-TSR. This should be set to low values or spaces to indicate a local TSR.

With Release 6.1.1 and above, a VTS-TSR name can be up to 8 characters. Previous releases supported only 4-character VTS names. For compatibility with existing 4-character VTS names, if the last 4 characters of an 8-character VTS name are low-values (binary zeroes), they will be ignored when determining which VTS-TSR to access.